Reasons to Believe

Early Life Was More Complex than We Thought

Is Genesis scientifically credible? According to the common narrative in our culture, scientific advance has rendered Genesis (and other creation accounts found in the Bible) untenable. Yet, if the Genesis creation “days” are viewed as long periods of time and the proper frame of reference is identified (Earth’s surface), remarkable agreement emerges between the Bible and the scientific record. (For a detailed discussion, see Navigating Genesis by my colleague Hugh Ross.)

At Reasons to Believe, we don’t stop at pointing out this astonishing agreement, we use Genesis and similar biblical texts to construct a scientific explanation for creation. We dub the result our testable creation model. When our model successfully predicts future scientific discoveries, it serves to further highlight the scientific accuracy of the creation accounts found in Scripture.

We’ve applied our creation model approach to the origin-of-life question (described fully in Origins of Life, coauthored by me and Hugh). Two key predictions of our origin-of-life model are: (1) life should appear early in Earth’s history; and (2) Earth’s first life should be inherently complex. Work over the last couple of decades largely satisfies both predictions. A preponderance of geochemical and fossil evidence indicates that life appeared early, perhaps as far back as 3.8 billion years ago. While the first life-forms resembled contemporary bacteria and archaea, other studies indicate that these organisms were metabolically complex.

Recent work by researchers from the University of Washington (UW) adds significant evidence for the early appearance of metabolically complex life.1 Based on a distinct geochemical signature in rocks that date 3.2 billion years in age, these investigators conclude that early life possessed the ability to fix nitrogen (N2).

Nitrogen Fixation

Nitrogen is a critical element, used to build DNA and proteins. Life can’t flourish without a ready supply of nitrogen. Nearly 80 percent of Earth’s atmosphere is composed of nitrogen, but this nitrogen is not bioavailable because of the strong bonds between its atoms. (Nitrogen consists of two nitrogen atoms joined by a strong chemical linkage called a triple bond.) A variety of abiotic processes can convert N2 into bioavailable compounds, such as ammonium (NH4+), but these processes are inefficient. If abiotic mechanisms were the only sources of bioavailable nitrogen, life wouldn’t be able to thrive. Without a more efficient means to generate bioavailable nitrogen-containing materials, planet Earth would be sparsely populated.  

That life is able to flourish on Earth today is thanks to nitrogen fixation. This critical metabolic process converts atmospheric nitrogen into nitrogen compounds readily accessible to organisms. Enzymes called nitrogenases mediate nitrogen fixation. The standard view has long been that nitrogen fixation began occurring on Earth only around 2 billion years ago, when nitrogenase enzymes first evolved in bacteria. Prior to this time, the limited amount of life that did exist would have struggled to eke out a living without an adequate source of bioavailable nitrogen.

Nitrogen Fixation Appears Earlier than Thought

The UW researchers have overturned the standard view. Apparently, life fared rather well on early Earth. The researchers studied the distribution of nitrogen isotopes in 3.2-billion-year-old rock formations found in northwestern Australia and in the eastern area of South Africa and found that microorganisms present on Earth at 3.2 billion years ago possessed the capacity to fix nitrogen. This is an unexpected result—naturalistically speaking. Eva Stüeken, the lead scientist for the study, says, “Imagining that this really complicated process is so old, and has operated in the same way for 3.2 billion years, I think is fascinating…It suggests that these really complicated enzymes apparently formed really early.”2 

In other words, this complex process that no one expected to emerge rapidly did so contrary to the predictions of evolutionary theory. How do evolutionary biologists account for this troubling new insight? Stüeken muses that “maybe its not so difficult for these enzymes to evolve.” 3 In other words, if nitrogenases appeared early on Earth with little time to evolve, then they must be easy to evolve.

There is no evidence to support this assertion. In fact, the prior expectation was that these enzymes (and the process of nitrogen fixation) would appear relatively late because they were too complex to evolve readily. To say that nitrogen fixation must be easily evolved because it appears early in Earth’s history constitutes circular reasoning, unless a mechanistic basis exists to show how it can readily emerge via natural processes.

On the other hand, our creation model predicts that early life on Earth would be metabolically complex and, lo and behold, it was. Our creation model for the origin of life readily accounts for this new insight and in doing so helps establish the scientific credibility of the Bible.

Subjects: First Life on Earth

Dr. Fazale Rana

In 1999, I left my position in R&D at a Fortune 500 company to join Reasons to Believe because I felt the most important thing I could do as a scientist is to communicate to skeptics and believers alike the powerful scientific evidence—evidence that is being uncovered day after day—for God’s existence and the reliability of Scripture. Read more about Dr. Fazale Rana

References:

  1. Eva E. Stüeken et al., “Isotopic Evidence for Biological Nitrogen Fixation by Molybdenum-Nitrogenase from 3.2 Gyr,” Nature, published online February 16, 2015, http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14180.html.
  2. “Ancient Rocks Show Life Could Have Flourished on Earth 3.2 Billion Years Ago,” ScienceDaily, published online February 16, 2015, http://www.sciencedaily.com/releases/2015/02/150216131121.htm.
  3. Ibid.